ABSTRACT
Different shapes of gold nanoparticles (NPs) have different enhancement effect in Surface Enhanced Raman Scattering (SERS). The polyhedral Au NPs have multiple angular structures, which show stronger enhancement effect than Au nanoplatelets. In recent years, the research on synthesis and properties of polyhedral Au NPs has attracted much attention. In this study the enhancement effect of the Au NPs in SERS was observed in Au NPs with the shape of dodecahedron, icosahedron, triangular plate and spherosome. Triangular Au NP films were prepared through a chemical reduction method using sodium borohydride as the reductant. As for synthesizing icosahedral Au NPs, Poly (vinyl pyrrolidone) is used as a capping agent and diethylene glycol is used as a reducing agent. Dodecahedral Au NPs were synthesized using icosahedral Au NPs as seeds. SERS spectra were detected for these three Au NPs as well as the traditional colloidal Au by using 4-mercaptopyridine and 4-mercaptobenzoic as probing molecules. Triangular Au NP films, icosahedral Au NPs and dodecahedral Au NPs were with average diameters of about 130, 100 and 120 nm. UV/Vis spectroscopy indicated that these three Au NPs had typical absorbance bands at 589, 598 and 544 nm. The results show that the Au polyhedron has better enhancement ability than the Triangular NPs.
ABSTRACT
Surface-enhanced Raman scattering (SERS) is spectroscopic technique with ultra-sensitivity and high selectivity and has attracted great attention because of the potential applications in various fields. P-aminothiophenol (PATP) is often used as SERS probe molecule because it is easy to adsorb on SERS substrates and produce high-quality SERS signals. TiO2 is extensively used as photocatalyst although its photocatalytic efficiency is still needed to be improved. Noble metal-modified TiO2 is one of current important techniques for maximizing the efficiency of photocatalytic efficiency. In this article, a kind of bifunctional SERS substrates, Ag/TiO2 nanotubes, with photocatalysis property were prepared, the TiO2 NTs were prepared by anodic oxidation and noble metal Ag nanoparticles were deposited on the surface of TiO2 NTs by photoreduction method. The photocatalysis of PATP on Ag/TiO2 NTs and on Ag mirror substrates were studied. The SERS signals of PATP were decreased with the ultraviolet irradiation time, however, on Ag mirror substrates, SERS intensity of PATP was slightly changed, which indicated the photocatalysis reaction of PATP on Ag/TiO2 NTs substrates. The kinetics analysis results indicate that the kinetics of the photocatalysis follows the first order of the dynamical reaction.
ABSTRACT
In the present review article, the methodology and recent advances of surface-enhanced Raman scattering (SERS) were described in detection of polycyclic aromatic hydrocarbons (PAHs). PAHs, a series of organic compounds, are of much concern because some of them as pollutants have been identified as carcinogenic, mutagenic and teratogenic compounds. They show low affinity to metallic surface, which confines applications of SERS to their detections. This article reviewed the development trends in PAHs analysis by using of SERS substrate modified by supramolecular system. And perspective SERS in PAHs studies have also been presented.
